The Acid Base Calculator The phot,ogrnph shows the Acid Bme Calculator in ime. It. is designed to in the teaching of lugstit hmie relationships, t,ypicsl of which is the IHtl, p l l , pOH, [ O W ] co~xlaticm. The inner slide card bears the mantissas of the lugmithms associated with the decimal values of p H and pOH. Clear, brief insi~.octionsare printed on the revelse side. Teachers can find the device helpfrd iu making up problems, as well as checking answess. Students not only call splve many problems directly, hut will learn lo recognize and become familiar with the fnndamentnl mathemntirr inv
